According to the Boise Police Department, they received a call from security personnel at Zoo Boise at 4:30 a.m. Saturday. Security guards say they spotted two men wearing dark clothing. One man was outside the zoo grounds while the other was inside the perimeter near the primate exhibit. When spotted both men ran; the one male inside the zoo ran further into the interior of the complex.

A search of the zoo by police and security failed to locate anyone.

During the search, a scream was heard and searchers were unsure if it came from an animal or a human. A Patas monkey was found with a head injury, lying near the perimeter fence where the security guard spotted one of the intruders.

Holly Peters, the zoo's veterinarian, arrived about 15 minutes later but the primate died around 6 a.m. Tests revealed the monkey died from blunt force trauma to its head and neck. Another Patas monkey that was in the same cage was not injured. The Sky Valley Chronicle reports no other animals were harmed or missing.

Steve Burns, the director of Zoo Boise, told the Idaho Statesman that staff reacted to the death with "a lot of tears, a lot of devastation." He also said, "The monkeys are always among the visitors' favorites. It's going to be hard to explain to kids that there are people in the world who would do something like this."

Police took blood found near where the monkey was found and are analyzing it to see if any of blood came from one of the suspects. Police also found a distinctive baseball cap that possibly came from one of the intruders. They are hoping the public can help them find its owner.

In a release put out by Zoo Boise, Patas monkeys are described as large animals that are 2 1/2 feet tall and weight 35 pounds. They can live up to 20 years in captivity.

The zoo had two Patas monkeys that were obtained three years ago from the Lowery Park Zoo in Tampa Bay, Florida. According to Burns, Patas monkeys are social animals and the zoo is concerned about the welfare of the survivor. Zoo Boise will either obtain another one or send the surviving Patas to another zoo.

Boise police are asking the public to contact them or Crime Stoppers if they recognize the baseball cap or have any other information.